Coated Abrasive Disk Comprising A Loop Fabric Layer and Preparation Thereof

ABSTRACT

A coated abrasive disk including (1) a loop fabric layer having a plurality of projected filament loops on one side thereof, (2) a carbon fiber textile layer or a glass fiber paper layer in a pre-dried state after impregnation-treatment with an adhesive resin, and (3) a coated abrasive material, which are sequentially stacked and tightly combined together, has an improved elasticity and high cutting performance characteristics.

FIELD OF THE INVENTION

The present invention relates to a loop fabric layer-containing coated abrasive disk which has an improved elasticity and high cutting performance characteristics, and a method for preparing said coated abrasive disk.

BACKGROUND OF THE INVENTION

A coated abrasive disk is usually prepared by coating an adhesive or pressure-sensitive adhesive on a back pad disk, and bonding the back pad to a disk form of a coated abrasive material (comprised of a backsheet and a layer of an abrasive material), followed by heat-pressing.

Recently, it has become more preferred to use in a sanding (grinding) a coated abrasive disk comprising as a back pad a loop fabric layer having several loops which is adhered to a hook fabric pad tool.

However, the coated abrasive disk prepared by laminating a loop fabric layer and a coated abrasive material using an adhesive, which shown in FIG. 1, has the problems of stiffness and low durability, which limits the use of such an abrasive disk.

SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the present invention to provide a loop fabric layer-containing coated abrasive disk which shows an improved elasticity and high cutting performance characteristics; and a method for preparing said coated abrasive disk.

In accordance with one aspect of the present invention, there is provided a coated abrasive disk which comprises:

(1) a loop fabric layer having a plurality of projected filament loops on one side thereof;

(2) a carbon fiber textile layer or a glass fiber paper layer bonded to the surface opposite to the surface having loops, the carbon fiber textile or glass fiber paper being in a pre-dried state after impregnation-treatment with an adhesive resin; and

(3) a coated abrasive material comprised of a backsheet bonded to the carbon fiber textile layer or glass fiber paper layer, and a layer of an abrasive material coated thereon.

In accordance with another aspect of the present invention, there is provided a method for preparing the coated abrasive disk which comprises placing disk forms of a coated abrasive material comprised of a backsheet and a layer of an abrasive material thereon, a carbon fiber textile or glass fiber paper, and a loop fabric in order such that the backsheet of the coated abrasive material faces the carbon fiber textile or glass fiber paper, the carbon fiber textile or glass fiber paper being in a dried state after impregnation-treatment with an adhesive resin, followed by applying heat and pressure to obtain a tightly combined stack of the coated abrasive material, carbon fiber textile or glass fiber paper, and loop fabric.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention will become apparent from the following description of the invention, when taken in conjunction with the accompanying drawings, which respectively show:

FIG. 1: a schematic diagram of a conventional loop fabric layer-containing coated abrasive disk;

FIG. 2: a schematic diagram of a loop fabric layer-containing coated abrasive disk in accordance with the present invention;

FIG. 3: a top side view of a reticular glass fiber textile plastic plate which is used in the preparation of the inventive coated abrasive disk;

FIG. 4: a longitudinal cross-sectional view of a stand mold having a shaft at its center which is used in the preparation of the inventive coated abrasive disk;

FIGS. 5 and 6: photographs of a loop fabric layer of the inventive coated abrasive disk; and

FIG. 7: a microscopic photograph (magnified up to 20 folds) of the loop fabric layer.

-   -   100: loop fabric layer     -   110: carbon fiber textile layer or glass fiber paper layer     -   120: coated abrasive material     -   122: backsheet     -   124: first adhesive layer     -   126: abrasive material     -   128: second adhesive layer     -   130: third adhesive layer

DETAILED DESCRIPTION OF THE INVENTION

The inventive coated abrasive disk has a structure comprising one loop fabric layer; one carbon fiber textile layer or glass fiber paper layer; and one coated abrasive material (comprised of a backsheet and a layer of an is abrasive material) which are sequentially stacked and bonded tightly together, wherein the loop fabric layer has a plurality of exposed and projected filament loops attached on one side thereof, to which carbon fiber textile layer or glass fiber paper layer bonded with the backsheet of the coated abrasive material is tightly attached. Such an inventive coated abrasive disk is illustrated in FIG. 2.

The loop fabric layer which is employed in the present invention has a plurality of projected and random-sized filament loops on one side thereof. The loop fabric layer may be made of a nylon, polyester textile or polyester/nylon mixed textile, and preferably has a specific weight of 70 to 120 g/m². The filament loops of the loop fabric layer have a thickness of 20 to 80 denier, preferably 30 to 50 denier.

The carbon fiber textile which is employed in the present invention is impregnation-treated with an adhesive resin and pre-dried before use. The adhesive resin may be incorporated into the textile in an amount ranging from 180 to 300 g/m². The pre-drying of the impregnation-treated carbon fiber textile may be performed at a temperature ranging from 100 to 140° C. for 3 to 5 min. The carbon fiber textile has a satin, leno or plain fabric pattern of 52˜70×24˜30 s/yarn (warp×fill) and a thickness of 0.1 to 0.32 mm, preferably 0.1 to 0.15 mm.

The glass fiber paper which is employed in the present invention is made of a mixture of 70 to 90% by weight, preferably 70 to 80% by weight of glass fibers and 10 to 30% by weight, preferably 20 to 30% by weight of wood fibers, and it may be prepared by a conventional sheet manufacturing process using 5-10 mm-cut glass fiber fragments having a thickness of 5 to 20 μm together with a wood fiber powder.

The glass fiber paper is also impregnation-treated with an adhesive resin and is pre-dried. The adhesive resin may be incorporated into the textile in an amount ranging from 90 to 200 g/m². The pre-drying of the impregnation-treated glass fiber paper may be performed at a temperature ranging from 80 to 100° C. for 1 to 3 min. The glass fiber paper before impregnation-treatment with the resin may have a specific weight of 45 to 80 g/m² and a thickness of 0.25 to 0.65 mm, and it is preferably of a flat shape.

The glass fiber paper provides an improved flexibility to the final coated abrasive disk and brings out an enhanced competitive price.

Representative examples of the adhesive resin employed in the impregnation-treatment of the carbon fiber textile or glass fiber paper include a phenol resin, epoxy resin, urea melamine, polyester resin, polyvinyl butyral, acrylonitrile-butadiene-rubber latex, degenerated heat-curable resin and a mixture thereof. A suitable phenol resin is a Rezole-type one having a solid content of 40 to 60% by weight and a viscosity of 400 to 700 cps at 25° C.

The coated abrasive material which is employed in the present invention may be a conventional one which is comprised of a backsheet and a layer of an abrasive material stacked thereon. Suitable for the backsheet are cotton textiles, polyester textiles, rayon textiles, polyester/cotton mixed textiles and polyester film (PET film), and particles of alumina (Al₂O₃), silicon carbide (SiC), alumina zirconia (AZ), ceramics (sol-gel), diamond and a mixture thereof having a mean particle size of 15 to 750 μm, preferably 30 to 250 μm, are preferred as the abrasive material

The elasticity of the coated abrasive disk depends highly on the particle size of the abrasive material, and the thickness of the carbon fiber textile or glass fiber paper layer.

The coated abrasive disk in accordance with the present invention is manufactured by placing, sequentially, the coated abrasive material, the carbon fiber textile or glass fiber paper impregnation-treated with an adhesive resin and pre-dried, and the loop fabric in the stand mold shown in FIG. 4, applying a pressure of 5 to 7 kgf/cm² to the stack of layers described above, and heating the resulting stack in an oven of 120 to 170° C., preferably 140 to 145° C. for 4 to 10 hrs to allow the adhesive resin impregnated in the carbon fiber textile or glass fiber paper to melt, resulting in the fusion of the component layers. In the above procedure, the backsheet of the coated abrasive material, and the projected filament loops of the loop fabric are placed upwards. The respective coated abrasive material, carbon fiber textile or glass fiber paper, and the loop fabric are pre-cut in the form of a disk. The use of the pre-dried carbon fiber textile or glass fiber paper makes it unnecessary to further use an additive in the final step.

In addition, in the inventive method for the preparation of the coated abrasive disk, it is preferred that the reticular glass fiber textile plastic plate shown in FIG. 3 or a plain fabric pattern of a glass fiber textile plastic plate coated with a Teflon resin is placed on the projected filament loops of the loop fabric during a heat-pressing process so that the flattening of the filament loops can be avoided. In case of employing the reticular glass fiber textile plastic plate, the filament loop side of the loop fabric has a reticular pattern generated by flattened loops. The plain fabric pattern of the glass fiber textile plastic plate coated with the Teflon resin is more preferred in terms of prevention of the excessive adhesion between the loop fabric layer and hook fabric pad tool adhered thereto.

The reticular or Teflon resin-coated and plain fabric-patterned glass fiber textile plastic plate used in the present invention may be manufactured by placing one to five glass fiber textiles impregnation-treated with a phenol resin and dried into the stand mold shown in FIG. 4, and then applying a pressure of 5 to 7 kgf/cm² thereto and heating the resulting stack in an oven of 120 to 170° C., preferably 145 to 150° C. for 1 to 5 hrs. The glass fiber textile may have a leno or plain fabric pattern of 5˜8×4.8˜8 s/yarn (warp×fill) and a thickness of 0.1 to 0.75 mm.

Photographs of the loop fabric layer of the inventive coated abrasive disk are shown in FIGS. 5 and 6, and its microscopic photograph (magnified up to 20 folds), in FIG. 7.

The inventive loop fabric layer-containing coated abrasive disk shows improved elasticity, flexibility and cutting performance characteristic, as compared to conventional disks prepared by laminating a loop fabric layer and a coated abrasive material using an adhesive. Thus, the inventive disk is useful for various applications including grinding of welding sites of car door frames and indented sides.

The following Examples and Comparative Example are given for the purpose of illustration only, and are not intended to limit the scope of the invention.

Example 1

Two 0.35 mm-thick glass fiber textile sheets (commercially available from Korea Fiber Company) with a leno fabric pattern of 5 s/yarn×4.8 s/yarn (warp×fill) which had been dried after impregnation-treatment with a phenol resin were each cut into a disk form having an outer diameter of 178 mm and an inner diameter of 23 mm, which were placed in the stand mold shown in FIG. 4, pressed at a force of 5 kgf/cm² using a 2 mm-thick steel plate (outer diameter: 180 mm, inner diameter: 23 mm) and heated at 145° C. for 2 hrs to prepare a reticular glass fiber textile plastic plate.

Cut into a disk form having an outer diameter of 178 mm and an inner diameter of 23 mm were a coated abrasive material P628 #80 Ywt (commercially available from Sun Abrasives Co. Ltd.,); a 0.13 mm-thick carbon fiber textile (No. H213, commercially available from Korea Fiber Company) with a 4-H satin fabric pattern of 52 s/yarn×28 s/yarn (warp×fill); and a nylon loop fabric having a specific weight of 120 g/m². The carbon fiber textile was impregnation-treated with a phenol resin (commercially available from Kolon), and pre-dried at 120° C. for 4 min. The amount of the phenol resin incorporated into the carbon fiber textile was 240 g/m².

The coated abrasive material #80, pre-dried carbon fiber textile and loop fabric disks were sequentially stacked from the bottom in the stand mold shown in FIG. 4. Then, the reticular glass fiber textile plastic plate prepared previously was placed thereon, pressed at a force of 5.5 kgf/cm² using a 2 mm-thick steel plate (outer diameter: 180 mm, inner diameter: 23 mm), and heated at 140° C. for 6 hrs to combine them tightly together, to obtain the coated abrasive disk in accordance with the present invention. In the above procedure, the backsheet of the coated abrasive material, and the projected filament loops of the loop fabric were placed upwards.

Example 2

The procedure of Example 1 was repeated except that one 0.12 mm-thick carbon fiber textile (No. 212, commercially available from Korea Fiber Company) with a 4-H satin fabric pattern of 74 s/yarn×37 s/yarn (warp×fill) which had been impregnation-treated with a phenol resin and pre-dried was cut and used, to prepare the inventive coated abrasive disk.

Example 3

The procedure of Example 1 was repeated except that one 0.10 mm-thick carbon fiber textile (No. 210, commercially available from Korea Fiber Company) with a 4-H satin fabric pattern of 64 s/yarn×24 s/yarn (warp×fill) which had been impregnation-treated with a phenol resin and pre-dried was cut and used, to prepare the inventive coated abrasive disk.

Example 4

The procedure of Example 1 was repeated except that one 0.15 mm-thick carbon fiber textile (No. H215, commercially available from Korea Fiber Company) with a 4-H satin fabric pattern of 58 s/yarn×30 s/yam (warp×fill) which had been impregnation-treated with a phenol resin and pre-dried was cut and used, to prepare the inventive coated abrasive disk.

Example 5

The procedure of Example 1 was repeated except that a processed glass fiber paper was cut and used in place of the carbon fiber textile, and a plain fabric coated with a Teflon resin was used as the glass fiber textile plastic plate, to obtain the inventive coated abrasive disk, wherein the processed glass fiber paper was prepared by impregnation-treating an untreated glass fiber paper (thickness: 0.28 mm, weight: 45 g/m²) made of a mixture of 80% by weight of 10 μm-thick glass fibers and 20% by weight of powdered wood fibers with a phenol resin (commercially available from Kolon) and pre-drying at 90° C. for 1 min. The amount of the phenol resin incorporated into the glass fiber paper was 90 g/m².

Example 6

The procedure of Example 1 was repeated except that a glass fiber paper was cut and used in place of the carbon fiber textile, and a plain fabric coated with a Teflon resin was used as the glass fiber textile plastic plate, to obtain the inventive coated abrasive disk, wherein the glass fiber paper was prepared by impregnation-treating an untreated glass fiber paper (thickness: 0.35 mm, weight: 60 g/m²) made of a mixture of 80% by weight of 10 μm-thick glass fibers and 20% by weight of powdered wood fibers with a phenol resin (commercially available from Kolon) and pre-drying at 90° C. for 1.5 min. The amount of the phenol resin incorporated into the glass fiber paper was 120 g/m².

Example 7

The procedure of Example 1 was repeated except that a glass fiber paper was cut and used in place of the carbon fiber textile, and a plain fabric coated with a Teflon resin was used as the glass fiber textile plastic plate, to obtain the inventive coated abrasive disk, wherein the glass fiber paper was prepared by impregnation-treating an untreated glass fiber paper (thickness: 0.6 mm, weight: 80 g/m²) made of a mixture of 80% by weight of 10 μm-thick glass fibers and 20% by weight of powdered wood fibers with a phenol resin (commercially available from Kolon) and pre-drying at 90° C. for 2 min. The amount of the phenol resin incorporated into the glass fiber paper was 200 g/m².

Comparative Example 1

A pressure-sensitive adhesive was coated on the backsheet of the coated abrasive material used in Example 1, and the loop fabric used in Example 1 was laminated to the coated backsheet such that the projected filament loops of the loop fabric were exposed, to prepare the conventional coated abrasive disk having an outer diameter of 178 mm and an inner diameter of 23 mm.

Characteristics Test

The characteristics of the respective coated abrasive disks obtained in Examples 1 to 7 and Comparative Example 1 were measured to determine the rotation failure speed, elasticity, flexibility, adhesive force between the loop fabric layer and the hook fabric pad, and cutting performance. The results are shown in Table 1.

TABLE 1 Coated Abrasive Disk Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Comp. Ex. 1 Rotation 32,000~35,000 34,000~36,000 34,000~36,000 28,000~30,000 23,000~24,000 28,000~30,000 28,000~30,000 24,000~26,000 Failure Speed (rpm)*¹ Elasticity (°)*² 145~150 140~145 130~135 150~155 140~145 150~155 150~155 65~70 Flexibility*³ 5.0 5.0 5.0 5.0 3.0 3.5 4.0 3.0 Adhesive 7.0~8.0 7.0~8.0 7.0~8.0 7.0~8.0 6.0~7.0 6.0~7.0 6.0~7.0 7.0~8.0 force(kgf)*⁴ Cutting 250~300 220~270 200~250 300~350 200~250 200~250 250~300 100*⁶  performance (%)*⁵ Relative cost 100.0  100.0  100.0  105.0  85.0  87.0  90.0  75.0  (%) Note: *¹The rotation number at which a coated abrasive disk is broken *²The angle to which a coated abrasive disk is unfolded within a predetermined time after folded at 180° *³The scale of the disk, pliableness →---------------- I --------------- ←stiffness 1 5 10 *⁴The force required for separating a 115 mm-wide and 230 mm-long rectangular loop-hook fabric sample *⁵The number of welding sites (expressed in percentage values) of a car door frame which was subjected to a sanding at a 7500 rpm air grinder *⁶The substrate cannot be subjected to further sanding

As can be seen from Table 1, the inventive coated abrasive disks of Examples 1 to 7 exhibit improved properties in terms of rotation failure speed, elasticity and cutting performance, as compared to the conventional coated abrasive disk of Comparative Example 1. Further, the results demonstrate that the inventive coated abrasive disks of Examples 5 to 7 comprising a glass fiber paper layer show remarkably improved flexibility and a lowered manufacturing cost by 10-15%.

As described above, the inventive coated abrasive disk shows improved elasticity and flexibility, high cutting performance and high adhesion to the hook fabric pad tool, as compared to conventional disks prepared by laminating a loop fabric layer and a coated abrasive material using an adhesive. Thus, the inventive disk is useful for various applications including grinding of welding sites of car door frames and indented sides.

While the invention has been described with respect to the above specific embodiments, it should be recognized that various modifications and changes may be made to the invention by those skilled in the art which also fall within the scope of the invention as defined by the appended claims. 

1. A coated abrasive disk which comprises: (1) a loop fabric layer having a plurality of projected filament loops on one side thereof; (2) a carbon fiber textile layer or a glass fiber paper layer bonded to the surface opposite to the surface having loops, the carbon fiber textile or glass fiber paper being in a pre-dried state after impregnation-treatment with an adhesive resin; and (3) a coated abrasive material comprised of a backsheet bonded to the carbon fiber textile layer or glass fiber paper layer, and a layer of an abrasive material coated thereon.
 2. The coated abrasive disk of claim 1, wherein the loop fabric layer is made of a nylon, polyester textile or polyester/nylon mixed textile.
 3. The coated abrasive disk of claim 1, wherein the loop fabric layer has a specific weight of 70 to 120 g/m².
 4. The coated abrasive disk of claim 1, wherein the filament loop side of the loop fabric layer has a reticular pattern generated by flattened loops.
 5. The coated abrasive disk of claim 1, wherein the carbon fiber textile is impregnation-treated with 180 to 300 g/m² of an adhesive resin and then pre-dried at a temperature ranging from 100 to 140° C.
 6. The coated abrasive disk of claim 1, wherein the carbon fiber textile has a satin, leno or plain fabric pattern of 52˜70×24˜30 s/yarn (warp×fill) and a thickness of 0.1 to 0.32 mm.
 7. The coated abrasive disk of claim 1, wherein the glass fiber paper is made of a mixture of 70 to 90% by weight of glass fibers and 10 to 30% by weight of wood fibers.
 8. The coated abrasive disk of claim 1, wherein the glass fiber paper before impregnation-treatment with the resin has a specific weight of 45 to 80 g/m² and a thickness of 0.25 to 0.65 mm.
 9. The coated abrasive disk of claim 1, wherein the glass fiber paper is impregnation-treated with 90 to 200 g/m² of an adhesive resin and then pre-dried at a temperature ranging from 80 to 100° C.
 10. The coated abrasive disk of claim 5, wherein the adhesive resin is selected from the group consisting of a phenol resin, epoxy resin, urea melamine, polyester resin, polyvinyl butyral, acrylonitrile-butadiene-rubber latex, degenerated heat-curable resin and a mixture thereof.
 11. A method for preparing the coated abrasive disk of claim 1 which comprises placing disk forms of a coated abrasive material comprised of a backsheet and a layer of an abrasive material thereon, a carbon fiber textile or glass fiber paper, and a loop fabric in order such that the backsheet of the coated abrasive material faces the carbon fiber textile or glass fiber paper, the carbon fiber textile or glass fiber paper being in a dried state after impregnation-treatment with an adhesive resin, followed by applying heat and pressure to obtain a tightly combined stack of the coated abrasive material, carbon fiber textile or glass fiber paper, and loop fabric.
 12. The method of claim 11, wherein the heat and pressure applied to the stack are in the ranges of 120 to 170° C. and 5 to 7 kgf/cm², respectively.
 13. The method of claim 11, wherein a reticular glass fiber textile plastic plate or a plain fabric pattern of a glass fiber textile plastic plate coated with a Teflon resin is placed on the projected filament loops of the loop fabric during the heat-pressing process.
 14. The coated abrasive disk of claim 9, wherein the adhesive resin is selected from the group consisting of a phenol resin, epoxy resin, urea melamine, polyester resin, polyvinyl butyral, acrylonitrile-butadiene-rubber latex, degenerated heat-curable resin and a mixture thereof. 